Tamping machine drive



Aug. 3l, 1965 J. E. ANDERSON TAMPING MACHINE DRIVE Filed March 5, 1964 INVENTOR. f/5M,

fig/.

United States Patent O 3,203,359 TAMPENG MACHINE DRIVE James E. Anderson, Ludington, Mich., assignor to `Iackson Vibrators, Inc., Ludington, Mich., a corporation oi' Iilinois Filed Mar. 5, 1964, Ser. No. 350,151 3 Claims. (Cl. 4165-27) This invention relates generally to railroad track maintenance machines and more particularly concerns a tr-ack wheel drive for such machines.

One of the most highly mechanized phases of railroad track construction and maintenance is the tamping -of ballast, the particular material used to nest and support the track cross ties. On track tampers are those which ride on the tracks 4being worked, and since their introduction several years ago, they have become larger as well -aS increasingly automated. One of the problem areas in the design of this equipment is in the track wheel or transport drive. The machines are massive; both moderate travel speeds and incremental start-stop movement is required; :and simple, responsive controls are needed `to complement the other `automatic aspects of operation as Well as be suitable for -fully automatic control.

Accordingly, it is the primary object of the invention to provide an improved drive for a tamper affording smooth, powerful, shock-free operation, under pushbutton control, that is well suited for -automatic programming. With more detail, it is an object to provide a tamper drive as characterized above that gives both a low indexing speed that is easily and conveniently settable for elivering maximum usable power under existing operating conditions and a relatively high travel speed that can be manually adjusted so as to provide full control over place-to-place movement of the tamper.

It is also an object of the invention to provide a tamper drive of the above type that is immediately responsive for both starting and stopping tamper movement.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE l is a diagrammatic showing of a tamper drive embodying the present invention; and

FIG. 2 is -a schematic wiring diagram of the control system for the drive of FIG. 1.

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning now to the drawing, there is shown in FIG. 1 a track wheel drive for an on-track tamper of which there is diagrammatically illustrated four flanged track wheels 11, a power plant or engine 12 and a rail clamping and jacking assembly 13. As those familiar with the art will understand, the wheels 11 carry the tamper on the track to be worked to the work area whereupon the rail clamping and jacking assembly 13 can be utilized to lift the track to the desired corrected elevation. Other mechanisms of the tamper, not shown herein, are employed to reposition and condition the track supporting ball-ast so as to maintain the track in the modified or corrected posit-ion.

3,203,359 Patented Aug. 31, 1965 The wheels 11 are driven by a reversible fluid motor 15 mechanically coupled to the wheels through a transmission 16 `and bevel gear assemblies 17 and 18. Power is supplied to the motor from a variable delivery pump 20 that is directly coupled in driving engagement to the tamper engine 12. The pump 20 draws uid from a reservoir or sump 21 and preferably takes the form of an axial piston pump with the pistons reacting against a swash plate which can be angularly adjusted by a lever 22. Thus, manual positioning of the lever 22 ypermits control of the pump output. It is contemplated that the engine 12 be driven at a constant efficient speed under governor conrol.

Pursuant to the invention, both an indexing circuit 23 and a traveling circuit 24 couple the pump 20 to the motor 15 through a directional valve 25. The valve 25 is 'a three-position valve centered by springs 26 and shifted to its alternating positions by solenoids 27 and 28.

On the motor side of the valve 25, there is a forward driving line 29, a reverse driving line 30, and a makeup or anticavitation circuit 31 including a ypair of valves 32 arranged to open the lines 29, 30 to uid flow from `a sump line 33. Thus, Kassuming the valve to be in its neutral position blocking fluid flow from the pump 20, rotation -of the motor 15 under the driving inertia of the tamper permits the motor to draw in additional oil through one of the check valves 32 and the line 33, in both directions of motor rotation, so that the motor and its feed lines 29, do not cavitate.

On the pump side of the valve 25, an input line 34, a drain line 35 and a brake line 36 all open to the valve 25. In 4the neutral or centered position of the Valve 25, the input line 34 is connected to the drain line 35 and the -brake line 36 is connected on the downstream side of a pair of check valves 37 to both the forward and reverse driving lines 29, 30. Thus, in this position of the valve 25, uid pressure in the line 34 is simply drained to the sump 21 and fluid ow through either one of the lines 29, 30, caused by coasting of the motor 15 under the inertia force of the tamper, drives fluid through the brake line 36 with the makeup circuit 31 replenishing the oil exhausted froml the motor.

Energization of the solenoid 27 shifts the valve 25, driving the schematic valve block downwardly, so that the input line 34 is connected to the forward driving line 29, the drain line 35 is blocked and the line 30, then serving as an exhaust line, is connected to the brake line 36. In this position of the valve 25 the motor 15 is driven so as to propel the tamper in a forward direction. Energization of the solenoid 28 shifts the valve 25, driving the schematic block upwardly, so that the input line 34 is connected to the reverse driving line 30 and the line 29, then serving as a motor exhaust line, is coupled to the brake line 36. Again, in this position of the valve 2S, the drain line 35 is blocked and uid flow through the reverse driving line 39 propels the tam-per in a reverse direction.

A pressure responsive brake valve 40 is interposed in the brake line 36 between the directional valve 25 and the sump 21. The valve 40 is normally biased in a closed direction and pres-sure in the line 36 acts, through a pilot line 41, to open the valve 40. Thus, 4the brake valve 40 creates a back pressure which can act against the motor 15 so as to -bring the latter to a quick stop after the directional valve 25 returns to its neutral position. The

brake valve 40 thus minimizes driving rotation of the motor under the inertia of the tamper and makes frictional braking unnecessary to quickly and reliably position the tamper.

For selectively opening one or vthe other of the indexing or traveling `circuits 23, 24, a pair of two-position valves 42 and 43 are provided. The valve 42 normally closes the indexing circuit 23 and, when its operating solenoid 44 is energized, the valve 42 shifts and opens the circuit 23.

The valve 43 normally opens the pump output to Vthe indexing circuit 23, and also to the rail clamping and track jacking, assembly 13. Energization of a solenoid 45, which operates the valve 43, shifts the Valve so that fluid flow from the pump is directed to the traveling circuit 24.

Proper pressures for the tasks performed are maintained in the circuits 23, 24 by a pair of pressure responsive valves 47 and 43, respectively. The valve 47 opens into the indexing circuit 23 and is set, in a representative embodiment, to open at a pressure of about 2,000 p.s.i. When opened, fluid in the indexing circuit 23 tlows through the valve 47 to an actuator 50 which, when supplied with fluid under pressure, shifts the pump controlling liver 22 to the oit position. Thus, the valve 47 is effective to keep the indexing circuit 23 pressurized up to its opening setting. At a greater pressure, the valve 47 opens and the pump output is halted by the actuator 50. At a lesser pressure, a spring 51 returns the actuator 50 to its inactive position and the control lever 22 is shifted so that more fluid is pumped into the circuit.

The valve 48 opens into the traveling circuit 24 and is set to open, again with reference to a representative embodiment, at a pressure of approximately 3,500 p.s.i. When the valve 48 opens, hydraulic tluid under pressure is directed to the actuator 50 so as to shut down the pump 20 in the manner described above. Hence, the valve 48, as does the valve 47, establishes a ceiling for the pressure in the circuit which it controls.

Preferably, a pair of check valves 52 and 53 are provided in the indexing circuit 23 so as to isolate the indexing from the traveling circuit. In addition a safety valve 54 is coupled directly on the output side of the pump 20 and is set, in the representative embodiment being reierred to, to open at a pressure of approximately 7,000 p.s.i. When open, the valve 54 exhausts uid to the sump 21.

To prevent the brake valve 40 from creating a back pressure on the motor 15 when the motor 15 is being driven, a line 55 connects both the indexing and the traveling circuits 23, 24 to the pilot portion of the valve 40 so that operating pressure in these circuits holds the valve 40 open. The valve 40 creates a back pressure, therefore, only when performing its tamper braking function.

When operating in the traveling mode, the tamper operator obtains driving control by manual manipulation of the pump lever 22. The lever 22 can be swung toward its oli position so as to slow down the tamper through track switches or under other conditions where a slower speed is called for. When in the indexing mode of operation, the power transmitted through the track wheels 11 can be regulated by setting a variable flow control valve 56 in the indexing circuit 23. As those familiar with the art will appreciate, it is desirable to move the tamper from one work setting to the next as rapidly' as possible. However, the amount of power which can be utilized by the track wheels 11 varies under different operating conditions. It the tracks are wet or otherwise made slippery, too much power generated by the motor 15 will simply cause the wheels to slip. In another case, movement of the tamper up or down a grade will change the maximum desirable amount of uid ow to the motor under indexing conditions. However, the provision of the valve 56 enables the operator to quickly set the drive for the maximum amount of power transfer consistent with working conditions.

For providing pushbutton control of the tamper drive, a two-position switch 60 and a pair of double throw pushbutton switches 61 and 62 are connected to solenoids 27, 28, 44 and 45 (see FIG. 2). The simple circuit interconnecting the switches 60-62 with the solenoids is such that with the switch 60 in the illustrated index position, pressing the pushbutton 61 results in energization of the solenoids 27 and 44. This shifts the valve 25 and the valve 42 so that fluid is directed through the indexing circuit 23 to the motor 15 in the direction to drive the tamper in a forward direction. Depressing the pushbutton switch 62 rather than the switch 6l. results in energization of the solenoid 28 along with the solenoid 44 so that the tamper is driven in a reverse direction by supplying fluid through the indexing circuit 23.

Turning the switch 60 to the travel position causes energization of the solenoid 45 when either the switch 61 or the switch 62 is actuated and, under these conditions, the indexing circuit 23 remains closed and the motor 15 is driven either in forward or reverse directions by tiuid directed through the traveling circuit 24.

I claim as my invention:

1. In a tamper having track engaging wheels and a power plant, a track wheel drive comprising, in combination, a variable delivery pump coupled in driven engagement to said power plant, a reversible fluid motor mechanically coupled in driving engagement to said wheels, a directional valve arranged to direct fluid to said motor for either forward or reverse driving, an indexing circuit coupling said pump and said valve, a traveling circuit coupling said pump and said valve, means in said circuits for selectively opening one or the other of the circuits, a pair of pressure responsive devices, one in each of said circuits, for varying the delivery of said pump so as to limit the pressure in said indexing circuit to an indexing pressure and the pressure in said travel circuit to a travel pressure that is higher than said indexing pressure, and a control for operating said means and said valve so as to drive the tamper in either forward or reverse direction at either index or travel speed.

2. In a tamper having track engaging wheels and a power plant, a track wheel drive comprising, in combination, a variable delivery pump coupled in driven engagement to said power plant, a manual control for selecting the output of said pump, a reversible fluid motor mechanically coupled in driving engagement to said wheels, a directional valve arranged to direct fluid to said motor for either forward or reverse driving, an indexing circuit coupling said pump and said valve, a traveling circuit coupling said pump and said valve, means in said circuits for selectively opening one or the other of the circuits, a pair of pressure responsive devices, one in each of said circuits, for varying the delivery of said pump so as to limit the pressure in said indexing circuit to an indexing pressure and the pressure in said travel circuit to a travel pressure that is higher than said indexing pressure, a variable iow control valve in said indexing circuit, and an electrically operated control circuit for simultaneously operating said means and said valve so as to drive the tamper in either forward or reverse direction at either index or travel speed.

3. In a tamper having track engaging wheels and a power plant, a track wheel drive comprising, in combination, a variable delivery pump coupled in driven engagement to said power plant, a reversible uid motor mechanically coupled in driving engagement to said Wheels, a directional valve arranged to direct iiuid to said motor for either forward or reverse driving, an indexing circuit coupling said pump and said valve, a traveling circuit coupling said pump and said valve, means in said circuits for selectively opening one or the other of the circuits, a pair of pressure responsive devices, one in each of said circuits, for varying the delivery of said pump circuit so that pressure in said circuit holds said pressure so as to limit the pressure in said indexing circuit to an responsive brake valve open whereby the valve offers no indexing pressure and the pressure in said travel circuit braking resistance when said motor is being driven.

to a travel pressure that is higher than said indexing pres- References Cited by the Examiner sure, a control for simultaneously operating sald means and said valve so as to drive the tamper in either or- UNITED STATES PATENTS ward or reverse direction at either index or travel speed, 3,060,953 10/62 Harburg 137--101 a uid return circuit for said rnotor having a pressure 3,149,464 9/64 Fauchere 60--53 responsive brake valve therein, and lines connecting said brake valve with said indexing circuit and said traveling 10 MILTON BUCHLER, PrimulaI Examiner. 

1. IN A TAMPER HAVING TRACK ENGAGING WHEELS AND A POWER PLANT, A TRACK WHEEL DRIVE COMPRISING, IN COMBINATION, A VARIABLE DELIVERY PUMP COUPLED IN DRIVEN ENGAGEMENT TO SAID POWER PLANT, A REVERSIBLE FLUID MOTOR MECHANICALLY COUPLED IN DRIVING ENGAGEMENT TO SAID WHEELS, A DIRECTIONAL VALVE ARRANGED TO DIRECT FLUID TO SAID MOTOR FOR EITHER FORWARD OR REVERSE DRIVING, AN INDEXING CIRCUIT COUPLING SAID PUMP AND SAID VALVE, A TRAVELING CIRCUIT COUPLING SAID PUMP AND SAID VALVE, MEANS IN SAID CIRCUITS FOR SELECTIVELY OPENING ONE OR THE OTHER OF THE CIRCUITS, A PAIR OF PRESSURE RESPONSIVE DEVICES, ONE IN EACH OF SAID CIRCUITS, FOR VARYING THE DELIVERY OF SAID PUMP SO AS TO LIMIT THE PRESSURE IN SAID INDEXING CIRCUIT TO AN INDEXING PRESSURE AND THE PRESSURE IN SAID TRAVEL CIRCUIT TO A TRAVEL PRESSURE THAT IS HIGHER THAN SAID INDEXING PRESSURE, AND A CONTROL FOR OPERATING SAID MEANS AND SAID VALVE SO AS TO DRIVE THE TAMPER IN EITHER FORWARD OR REVERSE DIRECTION AT EITHER INDEX OR TRAVEL SPEED. 